Dry docks

ABSTRACT

This specification discloses a dock gate of the flap type comprising at least one cantilever member and skins on either side of the gate, a buoyancy tank intermediate the top and bottom of the gate, proof means adjacent the bottom of the gate, and a claw formed in or adjacent to the dock sill, the claw having two surfaces against which the gate abuts, one surface being at each side of the gate, and the surfaces being spaced so that one side is higher than the other.

United States Patent [191 Andrew et a1.

1 1 Dec. 16, 1975 1 1 DRY DOCKS [75] Inventors: Paul Hugh Finden Andrew, Mt. Eliza; Kenneth Ewing Moxham, Vale Park, both of Australia [73] Assignee: Maunsell & Partners Pty. Limited,

Australia [22] Filed: Oct. 10, 1973 [21] Appl. No.: 396,298 [30] Foreign Application Priority Data Sept. 11, 1972 United Kingdom 42016/72 [52] US. Cl 61/64; 61/25 [51] Int. Cl. 363C 1/00; E02B 7/40 [58] Field of Search 61/64, 25, 22, 65, 8

[56] References Cited UNITED STATES PATENTS 3,543,521 12/1970 Aubert 61/25 3,756,032 9/1973 Solinas 61/25 FOREIGN PATENTS OR APPLICATIONS 950.756 2/1964 United Kingdom .1 61/64 573,919 12/1945 United Kingdom 61/64 Primary E.\'aminer.lacob Shapiro Attorney. Agent, or Firn1Cushman, Darby & Cushman [57] ABSTRACT This specification discloses a dock gate of the flap type comprising at least one cantilever member and skins on either side of the gate, a buoyancy tank intermediate the top and bottom of the gate, proof means adjacent the bottom of the gate, and a claw formed in or adjacent to the dock sill, the claw having two surfaces against which the gate abuts, one surface being at each side of the gate, and the surfaces being spaced so that one side is higher than the other.

14 Claims, 6 Drawing Figures US. Patent Dec. 16, 1975 Sheen 1 of3 3,925,999

US. Patent Dec. 16, 1975 Sheet 2 of3 US. Patent Dec. 16, 1975 Sheet30f3 DRY DUCKS NOTICE OF DEPOSIT BEFORE FILING DATE ACCORDED BY PATENT OFFICE The application which has become this patent was deposited in the Patent Office, but for the drawings, on Sept. 11, 1973.

This invention relates to improvements in docks and particularly to improvements in gates for docks and specifically dry docks of relatively great width.

For many years dry docks of medium to large width have been conventionally sealed by using the gate of the dock acting as a beam spanning between the vertical meeting faces at each side of the dock entrance. As the width of the dock opening becomes greater, it will be appreciated that the size of the beam becomes larger, and for wide docks, of the order of 160 or more feet, the gate becomes extremely expensive because the weight of the beam increases more rapidly than in direct proportion to the increase in length. Normally, dock gates are opened in one of two ways. In the first way, a flap gate is pivoted along its lower edge and opens outwardly and downwardly in front of the dock, and the ship being docked passes over the gate. Using the conventional operating procedure it is possible to use the beam partially or wholly as a buoyancy tank, but as the beam is normally located, when the gate is closed, above normal water level it is necessary to provide winching equipment to lift the beam from a condi tion at which the beam ceases to constitute a buoyancy tank floating on the surface of the water to a position at which the gate is fully closed. As gates become wider and heavier so this winching equipment has become more expensive.

The other conventional method of opening a gate has been to float the gate from its position either about a vertical pivot at one side, or completely free from the dock. Such movement is time consuming and also necessitates provision of a mooring for the gate, when a ship is entering or leaving the clock.

The object of the present invention is to provide a gate for a dock, and specifically a dry clock, which minimizes the disadvantages of previously known gates, particularly wide gates.

The invention, in its broadest aspect, includes a dock gate of the flap type adapted for location in a dock to seal off part of or the whole of the dock, characterized in that when the gate is closed it cantilevers from its lower edge.

In one specific form of the invention the gate comprises a plurality of cantilever members which are interconnected by a skin plate, at least on one side of the gate.

In a still further aspect, the gate may comprise a single cantilever extending across the width of the dock, the gate having outer and inner skins, the outer skin being in tension and the inner skin being in compression when the dock is dewatered.

The gate may make use of buoyancy tanks so located that the gate can be completely operated by filling or emptying buoyancy tanks without the necessity of providing any separate winching or lifting equipment.

Alternatively the gate can be arranged to be opened and closed by a combination of mechanical means and buoyancy, or by mechanical means alone.

The invention also includes a dock having such a gate.

In order that the invention may be more readily understood and put into practice, we shall describe fully one embodiment of the gate made in accordance with the invention and show certain alternative embodiments, the description being related to the accompanying drawings in which:

FIG. ll provides a cross section of the gate through the entrance of the dock;

FIG. 2 is a plan view of the gate;

FIG. 3 is an elevation of the gate looking from inside the dock;

FIG. 4 is a section along line 44 of FIG. 1; and

FIGS. 5 and 6 show modified forms of the gate, the views being similar to the view of FIG. 1.

This gate 1 may be considered to be some 210 feet wide and approximately 36 feet high above the sill of the dock. The gate is built around a number of main cantilevers 2, which are located at approximately 8 feet centres across the width of the gate. Between the main cantilevers there may be intermediate stiffeners which may in the form be T sections or other conventional members. As illustrated in FIG. 4, there are stiffeners 4 on the outer surface of the gate and stiffeners 3 on the inside of the gate in the buoyancy tanks only with both sets of stiffeners being spaced at approximately 2 centres. The gate skin 5 on the outer surface is achieved with any required material and is done in a manner known in the art, and normally by welding sheet material to the cantilevers 2 and the stiffeners 4.

The cantilevers are provided with two bearing surfaces, 6 and 7, surface 6 being on the outside of the gate adjacent to the lower edge of the cantilevers and surface 7 being on the inside of the gate and spaced approximately 7 feet above the lower edge of the cantilevers.

The inner bearing surface 7 is continuous and has a bearing strip 8 thereon, so that when the gate is in its closed position, as will be described hereinafter, the pressure acting upon the skin plate is transferred through the bearing strip 8 onto surface 9 of a claw 10.

In order to save weight it may be desirable to taper the lower portion of each main cantilever from the inner bearing surface 7 to adjacent to the outer bearing surface 6, but this is not essential.

In order to generally locate the gate it can be supported by horizontal pivots 11, which are located, in this embodiment, forwardly of the outer surface of the gate, which is a satisfactory pivotal axis for an inclined gate.

The pivot blocks 12 have slightly oversized holes, which permit the gate to have sufficient movement in the horizontal direction to ensure the claw makes good contact with the bearing strip 8 throughout the life of the strip, the pivots 1 1 being simply for general location and restraint.

Fitted within the depth of the gate and part way up the height of the gate but below low water level, there may be one or a plurality of buoyancy tanks 13. Preferably there is a single tank which lies between the main cantilevers 2 which act as baffles for the tank.

A second buoyancy tank 14 is also provided along the lower edge of the gate. This tank is normally flooded at all times when the gate is in operation and provides additional buoyancy to facilitate stepping and unsteppin g of the gate, as will be described hereinafter.

At the upper edge of the gate a roadway or walkway I5 is provided which may take any required form, and may be used as a permanent air tank for gate operating 3 procedure.

On each side of the gate, at the inner edge thereof, rubber quoin seals 16 are provided which, when the gate is closed, abut the sides of the dock so that the quoin seal 16, together with the bearing strip 8 provide the seal for the dock.

It will be appreciated that the closing surface surround at the dock entrance must be fonned so as to be complimentary with the gate. The most important part of this is the formation of the claw 10 which is formed in the concrete sill 20 at the base of the gate. The claw is formed to have the surface 9 against which bearing strip 8 of the gate can abut and a second surface 21 against which surface 6 of the gate can abut. The pivot blocks 12 are located just forwardly of the claw and are fixed to the concrete of the claw. A trash flap 22 is provided to protect the seal between the claw and the gate inner surface. Because of the outward lean of the gate, when closed, it is not necessary that a trash flap be provided on the outer bearing as the surface is protected by this lean, and when the gate is open, again, the outer bearing surfaces are protected.

If required the surface 6 may be able to be provided with a seal and an auxiliary quoin seal 23 can be provided on the outer surface of the gate so that when the gate is closed the claw can be dewatered and access can be obtained through an access shaft 24. The seals on the surface 6 and the auxiliary quoin 23 are normally only provided when the claw is to be dewatered and are placed in position specifically for that operation.

When the gate is open it is located on the harbour floor outwardly of the dock entrance, and in order to control the opening of the gate it is advantageous to provide a gate well 25 extending outwardly from the dock entrance which well acts as a dash pot when the gate is opening; the movement of water around the gate and over wall 26 of the well slows the opening of the gate to reduce impact.

Also, located in the gate well 25 there is a shock absorber 27 against which the gate abuts when it is fully opened. The open position of the gate is shown by dashed lines in FIG. 1.

In order to step the gate the buoyancy tanks 13 and 14 are aerated and the gate is floated to a position where it is beyond the dock with the end of the gate which is to be the lower end, pointing inwardly. At this .position the buoyancy tanks are partially filled with water. The amount of water in the buoyancy tanks is adjusted until the pivots 11 can be located in the required position on the pivot blocks 12 and when located keepers or the like are attached over the top of the pivot blocks. When the gate has been positioned the auxilliary buoyancy tank 14 can be completely filled with water.

In order to keep the gate closed mechanical latches are provided between the gate and the dock wall.

In use, when a ship is to be placed in the dock and the dock is full of water, it is only necessary to release the latches and fill the buoyancy tank 13 with water. As this fills there is an opening moment about the pivot point and the gate opens and is controlled by the rate of air exhaust. When the gate is fully open the main cantilevers abut the shock absorbers 27. The roadway is protected from damage by the wall 26.

The ship is then moved into the dock and at this time the buoyancy tank 13 is aerated which gives the tank buoyancy and the gate will ascend to its closed position where the latches are applied. The dock is then dewatered and, as the water level drops, the pressure of the Water on the outside of the gate causes a seal to be formed at the bearing points and the cantilevers each have a turning moment about the restraining points 6 and 7 in the claw. As the dock is dewatered the pressure acting on the skin plate increases and retains the gate in position. When it is required to open the gate it is only necessary to fill the dock with water, air is displaced in buoyancy tank 13 and the gate will open.

It can be seen that as the external pressure is divided between the main cantilevers a gate of any width can be designed and such gate should operate satisfactorily using the proposals of the invention.

In the embodiment so far described the gate is tilted outwardly when closed as, in this way, a gate can be provided having a readily accessible pivot and a claw which is easily accessible when the gate is open. At the same time access can be gained when the gate is closed by means of access shaft 24.

In FIG. 5 an alternative form of gate is shown which, when closed, is vertical. In this gate the pivot 30 is within the claw space and the operating buoyancy tank 31 is in the outer part of the gate to provide a turning moment about the pivot when the gate is operating. This form of gate is satisfactory in operation but it is difficult to gain access for maintenance of the pivot.

The gate of the embodiment of FIG. 6 is similar to that of FIG. 5 but in this case the buoyancy tank 32 is external to the gate providing a greater closing moment. This form of gate is, however, heavier than the previous forms and is slightly more difficult to step and unstep.

In each of the embodiments described the skin plate is preferably on the outer surface and is in tension when the gate is closed and the dock dewatered. Such an arrangement provides a high degree of safety. Should the gate be struck, for example, by a vessel there would tend to be only local damage, whereas with a conventional gate there can be compression instability across the full width of the gate. It is, however, possible to provide the gates of the invention with an inner skin plate either with or without the outer plate, and in some applications this may be desirable.

Instead of having an alternative form, the gate could be made as a single cantilever in which case it would normally be double skinned so that when the dock is empty the outer skin is in tension and the inner skin is in compression.

Further, we have described in our embodiments, gates which are opened and closed by use of buoyancy tanks. The invention is equally applicable to gates which are opened and closed by mechanical means and also to gates which use a combination of mechanical means and buoyancy.

Also we have described gates having a single buoyancy tank 13 but in some applications it may be desirable to provide a number of buoyancy tanks, some of which act as air tanks and others which can be selectively aerated or flooded to assist in the control of operation.

We claim:

1. A dock gate of the flap type located in a dock having a dock sill for sealing off at least part of the dock comprising in combination:

cantilever members rotatably mounted with respect to said dock sill,

a claw formed in or adjacent to said dock sill for receiving the lower end of said cantilever members when in their raised position,

load bearing surfaces on opposite sides of said claw against which said cantilever members abut when in their raised position, one surface being higher than the other to thereby provide restraint to the cantilever members of the gate.

2. In a dry dock having a dock sill, a flap type gate comprising a plurality of cantilever members interconnected by a skin on at least one side of the gate, a claw formed in or adjacent to said dock sill which receives the lower end of the cantilever members when in their raised position, load bearing surfaces on opposite sides of the claw against which the cantilever members abut when in their raised position, one surface being higher than the other, thereby providing a restraint to the cantilever of the gate.

3. A dry dock according to claim 2 wherein the load bearing surface which abuts the inside of the gate is higher than that which abuts the outside of the gate.

4. A dry dock according to claim 2 further comprising pivot members on the gate, and pivot blocks formed on the dock sill adjacent to the claw, said pivot members being rotatable in said pivot blocks, the pivot blocks being formed to permit limited non-rotational movement of the pivots relative thereto.

5. A dry dock according to claim 2 wherein the gate is provided with a single skin on the outside of the gate.

6. A dry dock according to claim 2 wherein the gate is provided with inner and outer skins; the outer skin being in tension and the inner skin being in compression, when the dock is dewatered.

7. A dry dock according to claim 4 wherein the gate is provided with at least one buoyancy tank spaced from the lower edge of the gate, said tank being spaced from said lower edge to provide a turning moment about said pivots.

8. A dry dock according to claim 7 wherein the buoyancy tank is located within the gate.

9. A dry dock according to claim 7 wherein the buoyancy tank is located externally of and secured to the outside of the gate.

10. A dry dock according to claim 2 further comprising having sealing means located at or adjacent to the load bearing surface which engages the inside of the gate.

11. A dock gate of the flap type located in a dock to seal off at least part of the dock comprising:

a gate member rotatably mounted with respect to a dock sill, said dock sill having a claw formed therein or adjacent thereto with said claw having two load bearing surfaces, said gate member when closed being partially located within said claw and abutting said two surfaces thereof, one surface being on each side of said gate, one surface being spaced higher than the other to thereby provide a restraining means against cantilever forces exerted on said gate member.

12. A dry dock as claimed in claim 11 wherein sealing means are provided along at least one of the two bearing surfaces.

13. A dry dock as claimed in claim 12 wherein sealing means are located along the inner bearing surface.

14. A dry dock as claimed in claim 11 wherein the gate has pivots associated with pivot blocks on the dock sill adjacent the claw, the pivot blocks being formed so as to permit movement of the pivots without local transfer between the pivot and the pivot block except hilst the gate is opening or closing. 

1. A dock gate of the flap type located in a dock having a dock sill for sealing off at least part of the dock comprising in combination: cantilever members rotatably mounted with respect to said dock sill, a claw formed in or adjacent to said dock sill for receiving the lower end of said cantilever members when in their raised position, load bearing surfaces on opposite sides of said claw against which said cantilever members abut when in their raised position, one surface being higher than the other to thereby provide restraint to the cantilever members of the gate.
 2. In a dry dock having a dock sill, a flap type gate comprising a plurality of cantilever members interconnected by a skin on at least one side of the gate, a claw formed in or adjacent to said dock sill which receives the lower end of the cantilever members when in their raised position, load bearing surfaces on opposite sides of the claw against which the cantilever members abut when in their raised position, one surface being higher than the other, thereby providing a restraint to the cantilever of the gate.
 3. A dry dock according to claim 2 wherein the load bearing surface which abuts the inside of the gate is higher than that which abuts the outside of the gate.
 4. A dry dock according to claim 2 further comprising pivot members on the gate, and pivot blocks formed on the dock sill adjacent to the claw, said pivot members being rotatable in said pivot blocks, the pivot blocks being formed to permit limited non-rotational movement of the pivots relative thereto.
 5. A dry dock according to claim 2 wherein the gate is provided with a single skin on the outside of the gate.
 6. A dry dock according to claim 2 wherein the gate is provided with inner and outer skins; the outer skin being in tension and the inner skin being in compression, when the dock is dewatered.
 7. A dry dock according to claim 4 wherein the gate is provided with at least one buoyancy tank spaced from the lower edge of the gate, said tank being spaced from said lower edge to provide a turning moment about said pivots.
 8. A dry dock according to claim 7 wherein the buoyancy tank is located within the gate.
 9. A dry dock according to claim 7 wherein the buoyancy tank is located externally of and secured to the outside of the gate.
 10. A dry dock according to claim 2 further comprising having sealing means located at or adjacent to the load bearing surface which engages the inside of the gate.
 11. A dock gate of the flap type located in a dock to seal off at least part of the dock comprising: a gate member rotatably mounted with respect to a dock sill, said dock sill having a claw formed therein or adjacent thereto with said claw having two load bearing surfaces, said gate member when closed being partially located within said claw and abutting said two surfaces thereof, one surface being on each side of said gate, one surface being spaced higher than the other to thereby provide a restraining means against cantilever forces exerted on said gate member.
 12. A dry dock as claimed in claim 11 wherein sealing means are provided along at least one of the two bearing surfaces.
 13. A dry dock as claimed in claim 12 wherein sealing means are located along the inner bearing surface.
 14. A dry dock as claimed in claim 11 wherein the gate has pivots associated with pivot blocks on the dock sill adjacent the claw, the pivot blocks being formed so as to permit movement of the pivots without local transfer between the pivot and the pivot block except hilst the gate is opening or closing. 